Final answer:
The two exceptions to complement nomenclature rules are C1q and C4, which deviate from the normal numerical sequencing due to historical naming conventions.
Step-by-step explanation:
The two exceptions to complement nomenclature rules are: C1q and C4. Typically, complement proteins are numbered C1 through C9, however, for historical reasons, the 'q' is added to the name of C1 (forming C1q) and C4 does not follow the numerical order in the sequence of activation. These designations stem from what was originally believed to be their order of discovery and importance in the complement cascade.